Update NEWS for 1.6.5.1

Update the release notes for 1.6.5.1 with information about the change in
gerrit 10331.

Change-Id: I0bd8d7aa3fa7aeb9a1a44f0aed06f85d6dcdcc06
Reviewed-on: http://gerrit.openafs.org/10332
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: Stephan Wiesand <stephan.wiesand@desy.de>